use nuxt plugin instead of function

composables/network.ts

@@ -2,6 +2,7 @@ import type { AsyncData, UseFetchOptions } from '#app'
 
 export function requestCore<DataT>(url: string, options: UseFetchOptions<DataT>) {
   // const config = useRuntimeConfig()
+  const {$mitt} = useNuxtApp()
   return useFetch(url, {
     baseURL: "https://cantyonion.site",
     retry: false,
@@ -25,7 +26,7 @@ export function requestCore<DataT>(url: string, options: UseFetchOptions<DataT>)
       // }
     },
     onResponseError({ response }) {
-      emitter.emit('eventBus', {
+      $mitt.emit('eventBus', {
         level: 'error',
         title: `HTTP错误：${response.status}`,
         message: response.statusText